Continuous freezing machine



Dec. 26, 1950 C. R. STOELTING ET AL CONTINUOUS FREEZING MACHINE Filed Aug. 4, 1948 2 Sheets-Shea?l 1 INVENTOILS CARL l?. STOELT//YG OLoF E. STAMBER@ E.FR'ED V/LTER ATTORNEY D66 26 1950 c. R. sToELTlNG ET AL 2,535,462

CONTINUOUS FREEZING MACHINE Filed Aug. 4, 1948 2 Sheets-Sheet 2 INVENTORS CARL R. S-roaLT//ve O/ or' E. .STA/wasn@ BY E. FRED VI/.TsR

ATTORNEY Patented Dec. 26, 1950 CONTINUOUS FREEZING MACHINE Carl R. Stoelting, conomo-woc, Blof E. lStambelg Waukesha, and Ernest F. Vilter, Milwaukee, Wis., assignors `to Industrial .Research Laboratories, Milwaukee, Wis., a corporation of Wisconsin Application August 4, 1948, Serial No. 42,404

(Cl. (S2-2114;)

.6 Claims. l

This invention relates to frozen confection machines of the type having a chamber con., tinuously receiving a mix at one end and discharging an edible frozen product at the other end. The terms lfrozen confection," tice cream and frozen custard are used as .equivae lents herein.

One object of this invention is to produce a frozen confection machine which is inexpensive to Vmanufacture and -to operate, increases the overrun without causing objectionable crystal formation ,or growth, .and will meet all health standards as regard cleaning and inspection.

Another object of this invention is to provide an improved refrigerating system for a continu. ons .type frozen custard machine. The refrigerating systems previously .employed .in machines of this type have generally been" of low efliciency. The present machine employs a Hooded evaporator with provision for -vaporizing and superheating the refrigerant while in contact `with the freezing chamber, thus obtaining highly efficient operation.

Another object oi this .invention is to provide an improved mutator for `propelling and agitat ing the mix during the course of its travel :from the receiving to the discharging end ofthe freezing compartment. This type of frozen custard machine requires la mutator which throws the mix against the refrigerated-walls of the vfreezing :if:

chamber and continuously scrapes `the frozen mix from the walls while propelling it through the chamber. The ypresent mutator additionally agitates or bea-ts the :mix in the proximity of the receiving end of the chamber. The beating zone of the ,freezing :chamber is maintained at a low temperature by means `of the improved refrigerating system. It is believed that the beating and the lmaintenance "of rapid freezing conditions in the beater, zone individually contribute to the 1.00% increase in overrun obtained with this machine vand in combination v-inodnoe very Satisfactory results without impairing the velvety texture desired especially in .production of frozen custard.

A lfurther object of :this invention is to pro. vide a simpliiied :mounting forV the scraper blades carried by the sha-ft in .the freezing chamber. Cooperating notches on the scraper blade and the carrying member result in ,a mounting which is readily cleaned and allows the blade to move to a limited extent as required by variations in ythe load.

`A still further object `of this invention is to provide a frozen custard machine having a horil2 zontal freezing chamber which `may 'be opened at both vends to permit ready access for .clean-.- ing and in Spectionof :the interior. This feature is of great importance since the health regulations of many :municipalities provide that no machine without such accessibility may be operated within the city. The reason for this will be obvious when it is considered that :dairy products are very susceptible to bacteria growth and must, therefore, be capable of being main..- tained in extremely sanitary condition.

Other objects and advantages will be pointed out in, or be apparent from, the specioa-tion and claims, as will obvious modifications `of the single embodiment shown in the drawings, in which:

Fig. 1 shows the general layout .of the freezer and its associated mechanism partly in section and with parts broken away: f

Fig..2 .is a front end view of the freezer taken along .line 2.-2 of Fig. ,1;

Fis. B is a rear end view as viewed from line 3-3 in Fig. 1 to illustrate the means for secure ing the back cover to the chamber and casing:

.'Eig. 4 is taken along line 4-f-r4 of Fis. 1 to show the end view of the beaters and the wet ro# friserated gas manifold positioned above the evaporator.; and i Fie. 5 shows the cooperating notch connection for mounting the scraper 'blade on the spiral.

Referring to the drawings in detail, Fig. 1 shows casing 8 containing insulated cylinder t0 donnine an open-ended cylindrical freezine chamber 1:2 in which the mutator. to be describes` in .detail hereinafter, picks up the kfrozen conf fection mix at the loitehand end of the chant,- ber and continuously discharges the frozen conefection at the other end. The confection vmix fiows, as regulated by valve It, from hopper vI4 into inlet 2u in cover 2i on the receiving end otr chamber 1 2 through watch glass i8 and pipes 22. y24 which are readily disconnected by means of any suitable telescopic joint :2li .the purpose ,ot

which will appear hereinafter.

inwardly :projecting stud 3u on front coverl head A3 2 serves as a bearing :for the hollow right hand end of mutatcr shaft 28. .Shaft 28 is also,

journalled in central opening 35 in the rear' head 2| through which it extends. The straight inside splines 33 on the left-hand end of thev shaft are connected to .shaft 34 which is driven in a clockwise direction (as viewed from right-` hand end of Fig. 1) by'electric motor 38 through" reduction gearing 40, .It will be apparent that the mutator shaft and the parts mounted thereon4 may be withdrawn from the right-hand end of the chamber when head 32 is removed by a method to be described hereinafter.

Spiral or worm 42 of relatively high positive pitch is mounted on the shaft immediately adjacent inlet 2li to pick up the mix and carry it forwardly, generally parallel to the axis of shaft 28, and feed the mix into the beater zone where beater blades 44, 45 (see Figs. 1 and 4) are mount# ed on opposite sides of shaft 28. As will appear clearly in Fig. 1 the blades on the opposite sides of the shaft lie in the same plane and reference to Fig. 4 will show that the outer eliptical edges of the blades conform with the circular interior wall of cylinder Ii] by virtuel of the inclination of the blades with respect to the shaft. Referring again to Fig. l, as the shaft rotates from the position illustrated, blades 44 on the near side of shaft 28 move upwardly and tend to propel the charge forwardly while at the same time blades 45 on the opposite side of the shaft will tend to. move that portion of the charge rearwardly. Thus blades'44 may be'said to be positively pitched in that they move the mix forward when the shaft is rotated. Conversely, blades46 may be referred to as negatively pitched. When the shaft has rotated 180, the blades as viewed in'Fig. 1 would appear to be inclined in the opposite direction, and the near blade would be negatively pitched blade 46. At this time the charge on the near side of the cylinder will tend to move rearwardly. Thus the beater blades 44, 46 cooperate to beat or oscillate the charge back and forth in this zone of cylinder i5. This beating action would,

in absence of worm 42, tend to keep the charge in the same zone in the chamber. Since worm 42 maintains a feed into the heater zone, the charge is' continuously moved toward the outlet but has a. generally oscillatory action superimposed on the forward motion. It should be understood, however, that screw 42 could be omitted and the blades 44, 46 inclined with respect to the shaft to produce more forward movement than rearward vmovement and thus convey the charge through the beater Zone while retaining the f.

beater action.

The discharge from the beater section into the final zone may be regulated, if desired, by means of annulus 48 having a central opening of larger diameter than shaft 28 to which it is secured. By varying the size of the opening between the shaft and the ring through which the charge must be forced, the state of the charge in the beater zone may be predetermined. It should be understood, however, that the ring need not be employedl since the refrigerating capacity may be so great as to obtain the proper state of the charge leaving the beater zone without impeding the flow. The charge leaving the beater zone is fed into and picked up by screw or worm i? which carriesthe mix toward the outlet. In this zone, as in the beater zone, the charge is thrown out against the refrigerating walls, which are continuously scraped by blades 58 to be described in detail hereinafter. Approximately the last two convolutions or iiights of screw 5t are of reduced pitch to increase the driving force pushing the frozen custard out of the outlet 52. This reduction in pitch of the last two flights allows use of a smaller motor and eliminates the complicated provision of an extra worm of small diameter in a co-axial, aligned discharge chamber as previously used in some of these machines. In both the beater zone and the worm section following the beater zone, the freezing of the mix on the refrigerated walls of the cylinder is' a continuous process. In the beater zone one scraper 54 is carried by three radially mounted arms 5E at an angle with respect to the interior of cylinder ld. As may be seen in Fig. l, scrapers 58 on screw 5t following the beater section generally overlap. All of these blades are carried by adjacent aligned portions of the screw flights at an acute angle with respect to the wall of cylinder ill with the leading or scraping edge facing in the direction of rotation. The blades are notched at 5&3 to loosely t and engage with notches 62 on worm 5o. Scraper 54 is similarly mounted on the three arms 56. This provides a simple joint which may readily be cleaned and, additionally, compensates for slight mutator shaft eccentricities, since centrifugal force and the load acting on the face of the blade cause the blade to move bodily outwardly to contact the wall of the cylinder.

Thus the charge entering chamber l2 through an orifice 2G is conveyed forwardly by worm 42 to the beater section where it is simultaneously beaten, thrown against and scraped from the walls to be discharged into spiral 5B where it is conveyed toward the outlet 52 while being continuously scraped from the walls. The reduced pitch portion of worm 5S adjacent outlet 52 increases the force pushing the charge out of the cylinder. Thus the mutator conveys the mix from the inlet to the outlet, beats the mix in a zone of the cylinder, and continuously scrapes frozen mix from the walls.

Cylinder 66 is concentric with and surrounds the major longitudinal portion of cylinder IU to define a flooded evaporator Gl for compressed liquid refrigerant entering at 65. A plurality of holes 68 along the top of the evaporator allows escape of wet refrigerant gas into manifold 'l0 defined by channel l2 welded or otherwise secured to the top of cylinder t6. The wet refrigerant gas fiovvs from the manifold into coil 'I4 wrapped around the receiving end of freezing chamber i2 in heat transferring relationship with the cylinder wall. Should any liquid refrigerant get into manifold lt, dam 16 prevents flow of the liquid into the coil I4 to insure that the coil contain only gaseous refrigerant. The superheated refrigerant gas leaving coil I4 at outlet i8 is con,

ducted to the compressor inlet by suction line 80.

Compressed liquid refrigerant flows from the condenser, not shown, through pipe 82 past electric stop valve 84 into thermostatic expansion valve 86 which regulates the flow into conduit 88,

.` discharging into the bottom of the evaporator at 65 to obtain the greatest refrigerating capacity in the beater zone. The thermostatic expansion valve is controlled by feeler bulb strapped on suction line 8f3 to regulate refrigerant flow to the evaporator valve in accordance with the degree of superheat and is preferably adjusted to substantially flood the evaporator. It is, of course, preferred that the bulb be pressure limit charged or have some equivalent means for preventing refrigerant ow to the evaporator during pull-down to permit use of a smaller motor driving the compressor. It will be noted that refrigerant feed line 88 is connected to the condenser outlet conduit 82 by means of by-pass check valve 92 to prevent building up excess pressure in the evapo-A rator.

This refrigerating system incorporates sound principles resulting in high eliiciency. The introduction of the compressed refrigerant at the beater zone insures greatest refrigerating capaci-y without objectionable crystal Aformation. The ,f

oscillatory beating action superimposed on .the general forward charge movement by the beaters in the rapid freezing zone is also thought to contribute to the increased overrun.

f As pointed out hereinbefore, it is Inecessary that cylindrical freezing chamber i2 be accessible from both ends to permit of proper cleaning and inspection of the interior in order to meet the strict standards set by some cities. Both end covers of the present machine may be readily removed without use of any tools. A portion of flanged cover 32 on the front end of chamber |2 snugly nts within the open end of chamber I2 with the hanged head seated against the casing. The cover is held in place by means of bar 94 extending across the cover with its left-hand bifurcated end (Fig. 2) snugly fitting under headed member 96 secured to the casing and its other end secured by means of a bolt extending through hole 98 in the bar and threaded into the casing. The bolt is provided With a hand wheel I so that it may be readily removed without the use of special tools. When the bolt has been removed, the bifurcated end of bar 94 may be withdrawn from its position under headed member 96 to allow removal of head 32 to expose the interior of the front end of the chamber.

Since the left-hand end of shaft 28 is splined to drive shaft 34 and the right-hand end is journalled on stud 3|] on head 32, the mutator, cornprising the shaft and its associated mechanism, may be freely Withdrawn from chamber l2 when front head 32 is removed.

As may be seen in Fig. 3, rear head 2| is secured to the casing in a similar fashion by means of bar |82 having a bifurcated end under headed member |04 and its other end provided with a hole receiving the hand wheel carried bolt. Bar |02 is, however, provided with a central opening through which mutator shaft 28 extends when splined to drive shaft 34. When bar |02 has been removed (as set forth in connection with bar 94'). and the telescopic connection 26 between feed conduits 22, 24 has been released, head 2| and conduit 24 may be removed to expose the rear end s of chamber |2.

We claim:

1. In a continuous freezer, a freezing cylinder adapted to continuously receive a mix at one end and discharge a frozen product at the other end, g g

an evaporator surrounding a portion of said cylinder and adapted to receive compressed liquid refrigerant, and a coil around another portion of the cylinder and connected to the evaporator to receive and superheat the gaseous refrigerant leaving the evaporator.

2. In a continuous freezer, a freezing cylinder adapted to continuously receive a mix at one end and discharge a frozen product at the other end, an evaporator surrounding a major portion of said cylinder, a valve controlled by temperature responsive means for regulating flow of compressed liquid refrigerant to the evaporator to substantially flood the evaporator, a manifold connected to and mounted on top of the evaporator to receive the wet gaseous refrigerant leaving the evaporator, and a coil around another portion of the cylinder in heat transmitting contact and receiving the wet gaseous refrigerant from the manifold to superheat the refrigerant,

-said temperature Aresponsive means .being respon! vsive to the temperature of the ysupelhea,ted refrig-f erant leaving `said .coil to maintain .said evaporator in a ooded state.

3. In a continuous freezer, a freezing cylinder containing a mutator adapted to continuously receive .a mix at one end .and discharge a frozen product at the other end, a cylindrical refrigerant evaporator surrounding a Yportion of said cy-lieder. a coil wrapped around said l.cylinder and receiving gaseous refrigerant yfrom ,said ,evaporator, and means for maintaining a supply of refrigerant to the evaporator.

4. In a continuous freezer, a casing containing a cylindrical freezing cylinder adapted to continuously receive a mix at one end and discharge a frozen product at the other end, a flanged cover seated against said casing with a portion of the head tting within said cylinder, said cover having a central opening therein, a retaining member removably mounted on the casing and extending across said cover to hold the cover seated in the cylinder and lagainst the casing, said member having a central opening aligned with the central opening in said cover, a hopper mounted on the casing and adapted to serve as a reservoir for the mix feeding into said one end of the cylinder, an inlet in said cover for receiving the mix from the hopper, a conduit connecting said hopper and said inlet and including joint means which may be readily disconnected to allow removal of said cover when said retaining member has been removed from said casing, another cover removably secured to said other end and having an opening therein adapted to serve as an outlet for said frozen product, and a mutator in said cylinder and including a shaft extending through the openings in said member and the first said cover at the one end of the cylinder and journalled on said other cover at the other end of said cylinder, said shaft being connected to a drive shaft adapted to rotate the mutator to convey the mix from the inlet to the outlet.

5. In a continuous freezer, a cylinder defining a freezing chamber, said chamber being adapted to receive a mix at one end and discharge la frozen product at the other end, a shaft mounted in said chamber, means carried by said shaft for maintaining a general forward movement of the mix from said one end to said other end, means mounted on the shaft in a zone of the chamber for superimposing on said general forward movement of the mix a relative back and forth beating movement, refrigerating' means including an evaporator receiving compressed liquid refrigerant and bein-g maintained in a flooded state, and a coil surrounding a portion of said cylinder receiving and superheating gaseous refrigerant leaving said evaporator, said coil being positioned adjacent the receiving end, and the inlet to said evaporator being proximate to the beating zone for maintaining a high rate of heat transfer in the beating zone.

6. In a continuous freezer, a freezing cylinder adapted to continuously receive a. mix at one end and discharge a frozen product at the other end, an evaporator surrounding said cylinder and having an inlet for compressed liquid refrigerant at the bottom of said evaporator, a manifold mounted on top of and connected to said evaporator to receive gaseous refrigerant leaving the evaporator, said manifold being connected to the suction line of a compressor, and a thermostatic expansion valve responsive to the refrigerant `temperature in the suction line-to regulate flow of compressed liquid refrigerant to said evaporator through said inlet to maintain the evapora tor in a substantially ooded sta-te.

CARL R. STOELTING.

OLOF1 E. STAMBERG.

E. FRED VILTER.

REFERENCES CITED The following references are of record in the 10 le of this patent:

Number Re. 21,8 27 772,656 1,500,061 2,050,975 2,080,971 2,324,395 2,338,362

8 UNITED STATES PATENTS Name Date Erickson June 17, 1941 Gerner Oct. 18, 1904 Dimm July 1, 1924 Morrow Aug. 11, 1936 Oltz May 18, 1937 Hoop July 13, 1943 Smith Jan. 4, 1944 Thomas June 25, 1946 Bartlett et a1 Apr. 18, 1947 

